Allowance for Loan Losses of Total Loans, Percentage

No definition available.

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- Definition

Allowance for Loan and Lease Losses, Related Loans, Percentage

+ References

No definition available.

+ Details

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Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Allowance for Loan and Lease Losses, Related Loans, Period Increase (Decrease)

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

The high maximum percentage of loan to value for consumer loans based on purchase price of the collateral.

+ References

No definition available.

+ Details

Name:	fnlc_CollateralizedConsumerLoansToIndividualsLoanToValueMaximumRangeHigh
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Data Type:	num:percentItemType
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Period Type:	instant

- Definition

The low maximum percentage of loan to value for consumer loans based on purchase price of the collateral.

+ References

No definition available.

+ Details

Name:	fnlc_CollateralizedConsumerLoansToIndividualsLoanToValueMaximumRangeLow
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The maximum percentage of loan to value for commercial real estate loans based on current appraisal information.

+ References

No definition available.

+ Details

Name:	fnlc_CommercialRealEstateLoansMaximumLoanToValue
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The regulatory maximum allowed ratio of loan portfolio to Company capital for construction and non-owner-occupied commercial real estate.

+ References

No definition available.

+ Details

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Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The actual ratio of loan amount to Company capital for construction and non-owner-occupied commercial real estate.

+ References

No definition available.

+ Details

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Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The regulatory maximum allowed ratio of loan portfolio to Company capital for construction loans.

+ References

No definition available.

+ Details

Name:	fnlc_ConstructionLoanPortfolioMaximumToCompanyCapital
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The ratio of loan portfolio to Company capital for construction loans .

+ References

No definition available.

+ Details

Name:	fnlc_ConstructionLoansActualLoanPortfolioToCompanyCapital
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Delinquent Period Before Consumer Loans Charged Off

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodBeforeConsumerLoansChargedOff
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The minimum amount of days past due at which residential loans are placed on non-accrual status..

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodBeforeResidentialLoansPlacedOnNonAccrualStatus
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Delinquent Period for Loans Charged Off

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodforLoansChargedOff
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Delinquent Period for Loans Charged Off, Period After Receipt of Notification from Bankruptcy Court

+ References

No definition available.

+ Details

Name:	fnlc_DelinquentPeriodforLoansChargedOffPeriodAfterReceiptofNotificationfromBankruptcyCourt
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans and Leases Receivable, Amortization Term

+ References

No definition available.

+ Details

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Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans and Leases Receivable, Commercial, Number of Loan Classes

+ References

No definition available.

+ Details

Name:	fnlc_LoansandLeasesReceivableCommercialNumberofLoanClasses
Namespace Prefix:	fnlc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Loan to Value Ratio

+ References

No definition available.

+ Details

Name:	fnlc_LoansandLeasesReceivableLoantoValueRatio
Namespace Prefix:	fnlc_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Loans and Leases Receivable, Number of Loan Classes

+ References

No definition available.

+ Details

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Namespace Prefix:	fnlc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Residential, Number of Loan Classes

+ References

No definition available.

+ Details

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Namespace Prefix:	fnlc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Term

+ References

No definition available.

+ Details

Name:	fnlc_LoansandLeasesReceivableTerm
Namespace Prefix:	fnlc_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of loans and commitments subject to review by an independent consulting firm each year.

+ References

No definition available.

+ Details

Name:	fnlc_OutstandingLoansAndCommitmentsSubjectByIndependentConsultingFirm
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of Total Reserve Allowance accounted for by Loan Loss Allowances

+ References

No definition available.

+ Details

Name:	fnlc_PercentageofTotalReserveAllowanceaccountedforbyLoanLossAllowances
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The high percentage of loan to value range for residential loans based on current appraisal information.

+ References

No definition available.

+ Details

Name:	fnlc_ResidentialLoansTypicalLoanToValueRangeHigh
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The low percentage of loan to value range for residential loans based on current appraisal information.

+ References

No definition available.

+ Details

Name:	fnlc_ResidentialLoansTypicalLoanToValueRangeLow
Namespace Prefix:	fnlc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 11B
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953423-111524

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 6.L.1)
-URI http://asc.fasb.org/extlink&oid=27010918&loc=d3e74567-122707

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (b)(1)(ii)
-URI http://asc.fasb.org/extlink&oid=82894903&loc=d3e15032-111544

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Balance Type:	credit
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- Details

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- Details

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- Details

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- Details

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Allowance for Loan Losses - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) loan_class	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loan classes \| loan_class	8
Percent of related loans	0.45%	0.39%
Increase (decrease) in qualitative portion	$ 1,027
Allowance for loan losses	$ 10,729	$ 10,138	$ 9,916	$ 10,344
Allowance for loan losses as a percent of total loans	0.92%	0.95%
Number of commercial loan classes \| loan_class	3
Loan-to-value percent, commercial real estate	80.00%
Number of residential loan classes \| loan_class	2
Construction loans, percent of capital	34.40%
Construction loans, maximum percent of capital	100.00%
Construction loans and non-owner-occupied commercial real estate loans, percent of capital	129.20%
Construction loans and non-owner-occupied commercial real estate loans, maximum percent of capital	300.00%
Outstanding loans and commitments subject by independent consulting firm	50.00%
Residential loans, loan to value percent minimum	75.00%
Residential loans, loan to value percent, maximum	80.00%
Consumer loans, loan to value percent, minimum	80.00%
Consumer loans, loan to value percent, maximum	90.00%
Commercial \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 434	$ 396	580	823
Loan maturities	2 years
Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 692	807	893	1,060
Loan maturities	300 months
Loan to value ratio	0.8
Residential
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan to value ratio	0.80
Amortization term (in years)	30 years
Delinquent period before residential loans are placed on non-accrual status	90 days
Delinquent period for loans charged off	180 days
Delinquent period for loans charged off after receipt of notification	60 days
Residential \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 36	44	24	20
Loan maturities	1 year
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 545	559	$ 566	$ 542
Delinquent period before consumer loans are charged off	120 days
Unallocated Reserves
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 642	$ 1,258
Percent of total allowance reserve	6.00%	12.40%
Unallocated Reserves \| Commercial \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 0	$ 0
Unallocated Reserves \| Home Equity LIne of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves \| Residential \| Construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	0	0
Unallocated Reserves \| Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Allowance for loan losses	$ 0	$ 0